This invention relates to the field of compatible AM stereophonic receivers and more particularly to the use of phase detection and non-linear amplification for deriving the L and R signals.
A system for transmitting and receiving a compatible AM stereophonic signal of the form (1 +L +R) cos (.omega..sub.c t+.phi.) where .phi. is arc tan [L-R)/(1+L+R] was disclosed in a patent application Ser. No. 674,703, assigned to the same assignee as is the present invention. In the receiver of that application, and in all others now known, a correction factor proportional to cos .phi. is derived in the receiver. Wherever it is necessary in the particular receiver circuitry, signals including cos .phi. are divided by the correction factor to provide the original sum and difference signals and, eventually, the L and R signals to the stereo outputs. It would be advantageous to utilize tangential correction since less correction is required for a given signal level.